1. Field of Invention
The present invention relates to hammers in general and, in particular, to a claw hammer provided with an improved extendable fulcrum to reduce the effort required in removing nails.
2. Prior Art
Heretofore, various modifications have been provided to conventional claw hammers in order to aid the carpenter in removing nails which, among other reasons, are retained within a wood surface and have been driven in improperly or have struck a knot and cannot be driven completely therein. This type of problem occurs frequently and the carpenter is obliged to waste precious amounts of time to remove said nails from the wood. Furthermore, said carpenter must be careful not to mar the surface of the wood from which said nails are being pulled. As is well known, the more difficult the nail removal, the more likely there will be damage to the nail bearing surface on use of the claw hammer.
Many are those who have attempted to remediate to this problem, either by attaching auxiliary fulcrum means to the hammer head or by adding intrinsic extendable fulcruming mechanisms inside the hammer proper.
Belonging to the first group, and worth considering, are the following U.S. Pat. Nos. 2,643,854 and 2,553,102. Belonging to the second group and equally worthy of consideration are the following U.S. Pat. Nos. 2,589,046, 2,589,047, 2,741,456, and 4,422,620. However, hammer head add-ons have proven to be unreliable because they substantially change the shape of the hammer head, thereby causing said head to be disproportionate and in effect becoming a hindrance and interfering with the accomplishment of the work at hand. They also tend to fall off during constant use of the hammer.
Conversely, extendable fulcrums of the prior art have been bulky, complicated in their manufacturing, since most of them make use of notches, latches, springs, etc. . . An exception is U.S. Pat. No. 2,741,456 wherein the extruding part is not a fulcrum, but a pry bar. However, in most of the above mentioned references of the second group, this type of adjustable fulcrum has a considerable number of disadvantages. First, the plunger is difficult to manufacture and cannot be obtained as a standard part. The notches weaken the plunger and provide places where it can easily break as well as interrupt spacing. The plunger must be kept in an orientation where the latch will mesh with one of the notches, thus complicating the internal construction of the handle. The notches will wear and eventually the plunger will not be able to lock firmly in position. Finally, while using this configuration of parts, if the latch is accidentally struck during rebounding off the strike surface, the fulcrum will prematurely eject. On the other hand, in the case of U.S. Pat. No. 4,422,620, which in one embodiment, makes use of a solid cylindrical rod for a fulcrum rod, said fulcrum rod is locked in place by a set screw. Slippage and marring of said fulcrum rod would certainly occur when brute strength is applied to remove a nail that offers even moderate resistance. In the case of U.S. Pat. Nos. 2,589,046 and 2,589,047, the extended fulcrums are kept in their operational position by the pulling action of a tension spring, hardly a dependable and strong embodiment.